1. Technical Field
The present invention relates to a liquid supplying device and a liquid ejection apparatus.
2. Related Art
An ink jet printer (hereinafter referred to as a printer) is widely known as a liquid ejection apparatus for ejecting liquid onto a target. The printer has a recording head (liquid ejection head) mounted on a carriage that reciprocates. The recording head is supplied with ink (liquid) from an ink cartridge (liquid container) mounted on the printer at a predetermined location. The ink is ejected to a paper, which serves as a target, from a nozzle formed in a nozzle formation surface of the recording head to perform printing.
Such a printer is disclosed in, for example, JP-A-2005-95861. The printer is provided with a carriage including a valve unit (liquid supplying device) having a liquid supply passage for supplying ink from an ink cartridge to a recording head. In the valve unit, a pressure chamber (liquid storage unit) for temporarily storing ink is defined in the liquid supply passage. The pressure chamber is formed by a flow passage formation body, which has a fixed shape, and a flexible film. Further, the pressure chamber includes an entrance, which is in communication with the upstream side of the liquid supply passage extending from the ink cartridge, and an exit, which is in communication with the downstream side of the liquid supply passage extending from the recording head.
An open/close valve that opens and closes to regulate the flow of ink from the entrance to the pressure chamber is arranged in the liquid supply passage. The film is displaced when sensing negative pressure generated as the ink in the pressure chamber decreases due to ink ejection from the recording head. The displacement of the film opens and closes the open/close valve to adjust the supply pressure of the ink supplied from the ink cartridge to the recording head.
To enable multi-color printing, recent printers include a plurality of ink cartridges containing different colors of ink. Further, a plurality of nozzle rows respectively corresponding to the ink cartridges are formed in the nozzle formation surface of the recording head. A plurality of liquid supply passages are formed between the ink cartridges and the corresponding nozzle rows. The liquid supply passages enable ink to be supplied from the ink cartridges to the corresponding nozzle rows. A pressure chamber is arranged in each liquid supply passage. The displacement of a film opens and closes an open/close valve to regulate the inward flow of the ink. The pressure chamber, which is formed by a flow passage formation body and a film, is arranged in each liquid supply passage. The printer disclosed in JP-A-2005-95861 has a similar structure, and the printer includes two valve units, each having two liquid supply passages with a pressure chamber arranged in each liquid supply passage.
However, in the structure in which a liquid supply passage and a pressure chamber are formed in each of the plurality of valve units, the flow passage formation body and the film that forming the pressure chamber differs between each valve unit. Thus, the liquid supply passages and the pressure chambers arranged in different valve units may differ between one another in the behavior of the negative pressure generated in the pressure chamber, the open/close timing of the open/close valve that corresponds to the displacement of the film based on the negative pressure, and the supply of the ink through the liquid supply passages. Accordingly, the ejection state of the ink ejected from the recording head varies between the nozzle rows, and satisfactory printing cannot be performed.